Pronounced: "Ditkey," it is short for "Down To Kick It"
DTKI is similar to: "You wanna hang out?" or, "You want to party?"
DTKI is usually used in just a short sentence, with out waiting for a response. On the phone, it requires the person who was asked if they are DTKI to call back with their response.

Sasha: Hey Jake, call upCamille and see if she wants to hang out today.
Jake: YOU DTKI? *(hangs up phone)*